Question: The 3rd and 5th terms of an arithmetic sequence are 17 and 39, respectively. What is the 7th term of the same sequence?
Let the first term of the arithmetic sequence be $a$, and let the common difference be $d$.  Then the third term is $a + 2d = 17$, and the fifth term is $a + 4d = 39$.  Subtracting these equations, we get $2d = 22$.

Then the seventh term is $a + 6d = (a + 4d) + 2d = 39 + 22 = \boxed{61}$.